Planning for retirement is never easy, especially as there’s no universal figure for what people are going to need. According to Clever Real Estate, retired Americans estimate someone would need $823,800 in savings and investments to retire comfortably in 2026.

For anyone worried about not being able to build that kind of retirement fund, a lottery ticket is tempting. But there’s another potential (albeit unlikely) source of that kind of windfall: rare coins. There are coins which, if sold, would likely net seven figures, and some could still be hiding in inherited boxes or long-forgotten safes.

Though their owners would struggle to actually “spend” them, these eight coins have potential values that could rival a retirement portfolio, according to USA Coin Book.

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Most 1943 pennies were made from steel due to wartime copper shortages, though a very small number were struck on leftover copper blanks, and only one Denver-minted example is known to exist. Depending on condition, values can range from hundreds of thousands to more than $2 million. This coin is heavily counterfeited, so authentication is important.

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The quarter eagle was first produced in 1796, and there are two versions, one with stars on the front and one without. Both versions are valued at over $1 million in mint condition, the version with stars up to almost $1.7 million and without stars over $2.4 million.

Only seven examples of this coin, with the head facing right, are known to exist, and some haven’t been seen since the 1940s. If anyone was to come across such a rare coin in a forgotten collection, they could be looking at a retirement fund of more than $2 million if it was in mint condition.

The US Mint has no official record of producing this coin, yet about 15 are believed to exist. Examples in uncirculated mint condition can be worth more than $2 million.

Carson City mint gold coins are incredibly rare and highly collectible. Uncirculated examples of this $20 coin have been valued at nearly $2 million, making it one of the most valuable 19th-century U.S. gold coins around.

This variety uses an earlier Liberty head design and distinctive large lettering on the reverse. Proof examples have been valued at more than $1.9 million.

This extremely rare gold coin is hard to find. Well-preserved examples can be worth more than $1.8 million, showing how a single coin can be worth more than most retirement accounts.

In the 1790s, some silver dollars were altered to ensure proper weight by adding a small silver plug to the center before striking. In mint condition, these coins could have a value of around $1.8 million.

Like a lottery win, rare coins aren’t a replacement for disciplined saving or investing. Still, collectibles like this can carry extraordinary financial weight. For anyone with old coins passed down through family or stored away years ago, a professional appraisal may reveal something far more significant than face value.

Editor’s note: all coin values were sourced from USA Coin Book.

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This article originally appeared on GOBankingRates.com: Here Are 8 Coins You Should Never Spend — They Could Pay for Your Retirement